Scanning-Beam Interference
LithographyGratings are written with Scanning-Beam
Interference Lithography (SBIL) using the nanoruler. Utilizing an array of custom processing
equipment and techniques, PGL can process a wide range of optical substrates.Current
maximum size is about 93 cm x 60 cm. Plans are underway to make a machine
with 1.3 to 1.5 meter capability

SBIL produces a highly accurate linewidth that results in excellent diffraction
efficiency that is both uniform and repeatable from part-to-part. By precise
control of the grating exposure and phase, PGL’s SBIL technology is the
only known technique that allows for correction of wavefront errors in substrates
and apodization of incident beams. The scanning technique of SBIL overwrites
with a gaussian distributed energy band of laser light that provides a high
level of dose control resulting in consistent aspect ratio, high efficiency,
and period repeatability of over 10ppb part-to-part.

PGL
and MIT are working toward writing more complex gratings with Variable-Period
Scanning-Beam Interference Lithography (VP-SBIL). VP-SBIL capacity
allows for a quick changeover for periods from 200 nm to 25 µm. VP-SBIL
has been tested at 100, 200, 500, 1000, 1740, 2500 and 5000 lns/mm.Due to the high degree of automation in the tool,
period can be changed and ready to write on large samples in < 1 hour.
PGL now writes gratings with two or more periods on the surface. Coarse
gratings are used for measurement of grating thickness.

Ion Beam EtchingPGL uses a large area reactive ion etcher to etch
photoresist gratings into various silicate glasses.Here a grating is mounted in the etch
chamber. The ion source is in the foreground.
The PGL Ion Etcher uses a scanning method to achieve high etch uniformity.
Etched MLD diffraction efficiency
is uniform and high across the part.
PGL can accurately map diffraction efficiency
across large parts to determine etch uniformity.

Sandia Compressors (600mm x 210 mm)C3 DE Average 0.97

C5 DE Average 0.98

C1 DE Average 0.965

Liquid Film Coating

PGL's
meniscus coater applies photoresist to the substrate. The meniscus coater
pulls the substrate over a meniscus of fluid. Small substrates are held
upside down by a vacuum while large substrates are held by a groove in
the substrate.

CoatingA 1.1 meter chamber is used for development of
complex multilayers and energetic processes such as ion-assisted deposition.